IE 5.5 not browsing the Internet

Use Windows Explorer and browse on over to c:\Documents and Settings\logonname\Local Settings\Temporary Internet Files and delete all the folders under Content.ie5 and delete all the files/cookies in content.ie5 as well.

That will clear out anycorrupted files from IE5. And you should be able to broswe with ie5.5 afterward without any problems.

Some other things to check using TOOLS : Internet Options...IE before digging deeper:
Content : Content Advisor
Advanced : HTTP 1.1 Settings
make sure Use HTTP 1.1 through proxy connections is unchecked
Connections
Sometimes, when a page is not found (404 error) IE offers the option to automatically detect & correct your settings. This causes settings for a Proxy Server to be turned on. Unless you are setup for using a proxy server, this will effectively disable your IE. So, if you're sure you NEED to have the proxy server, don't follow these steps. Most installations ( dialup, cable modem, dsl ) DO NOT use a proxy server. It is something your administrator would have explicitly have had to enable and setup.
If you usea DIALUP
select (highlight) the connection you're using.
in the Proxy Server section, make sure to uncheck the Use Proxy Server box
If you use a LAN
click LAN Settings...
make sure ALL the check boxes are NOT selected

Save the settings.
Close IE
Reboot & retry